A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal powe...A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal power plants. The P1-P2 method is used in the present study, together with the thermoeconomic analyses of feed water heaters.展开更多
Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar wat...Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar water heaters as a result of their greater surface area exposed for sunlight absorption. Water-in-glass evacuated tube solar water heaters are widely used as compared to heat-pipe solar water heaters due to their short payback periods. In this study, the performance of water-in-glass evacuated tube solar water heater is investigated through experiments under the climatic conditions in Kenya. The results revealed a daily efficiency range of 0.58 - 0.65 and a daily final outlet temperature greater than 55<span style="white-space:normal;">°</span>C given an initial temperature of 25°C.展开更多
A new kind of thermoelectric heat pump water heater for kitchens exhaust heat recovery was presented,and its performances were investigated under different operating voltages.The experiment results show that the coeff...A new kind of thermoelectric heat pump water heater for kitchens exhaust heat recovery was presented,and its performances were investigated under different operating voltages.The experiment results show that the coefficient of performance decreases and the temperature difference between the hot and cold sides becomes larger with the increase of the operating voltage,but the heating time becomes short.The higher the temperature of water,the greater the temperature difference between the hot and cold sides,leading to a smaller coefficient of performance.Under an exhaust temperature of 36 ℃,the coefficient of performance decreases from 1.66 to 1.22 when the temperature of water increases from 28 ℃ to 46 ℃ with operating voltage 16 V.Performance tests illustrate that,compared with the conventional electrical water heaters,the new kind of thermoelectric heat pump water heater is more coefficient.展开更多
In order to meet the demands of service life and the synthetical performance/price ratio of stainless steel in the solar water heater industry,the low molybdenum ultra-pure ferritic stainless steel(FSS) B445J1M was de...In order to meet the demands of service life and the synthetical performance/price ratio of stainless steel in the solar water heater industry,the low molybdenum ultra-pure ferritic stainless steel(FSS) B445J1M was developed at Baosteel.In this study,comparative studies were carried out on the mechanical properties,the formability and the corrosion resistance of B445J1M,304 and 444,and the advantages and application fields of B445J1M were summarized.展开更多
China is the largest solar water heater producer and market in the world.Despite the fast growth and an installed capacity that accounts for the majority of the global gross,China's per capita solar hot water capa...China is the largest solar water heater producer and market in the world.Despite the fast growth and an installed capacity that accounts for the majority of the global gross,China's per capita solar hot water capacity is still very low,implying a huge margin of market potential;and the recognition of the industry in the global market is handicapped by the scattered scale of production and inconsistent product quality.To ensure continued growth of China's solar water heating(SWH) industry,Chinese Government has established a series of national SWH standards,three national testing centers,and a certification program to lay the foundation for the development of the Golden Sun product labeling system.China General Certification Center(CGC) developed the Golden Sun product certification and labeling system on a pass/fail basis evaluating with established criteria.The system was designed to help manufacturers acclimate to explicit consistent requirements and to identify and fix the deficiencies in the design and execution of the program itself.Timely revision and integration of the national standards are recommended to accommodate the test procedures and requirements to new technologies and the evolving SWH market.Strict implementation of the Golden Sun certification and labeling system are suggested to avail improving the quality control and forging internationally reputable brands of Chinese solar water heating products.展开更多
In this paper we describe an integrated collector storage solar water heater for the North Western region of India for use as domestic water heater during the winter season and present the experimental results of temp...In this paper we describe an integrated collector storage solar water heater for the North Western region of India for use as domestic water heater during the winter season and present the experimental results of temperature stratification. The system consists of a steel water storage tank with azimuthal orientation such that its walls face south east, south west, north east and North West directions. The sunlit walls (south east and south west) and the top cover surface of the storage tank are covered with transparent insulation material (TIM) and the off-sunlit sides with opaque insulation. Experimental results show that the top layer is at the highest temperature. The top layer is drained using a new design of the outlet. The system can be used in rural areas or as a pre heater in more affluent households. The system can return the cost of conversion of the storage tank into a Solar Water Heater in one winter season by saving the cost of electrical energy required for heating water during winter months.展开更多
Two solar water heaters of 100 liter and 200 liter were installed on the roof-top of electronics laboratory at Old Academic Building (OAB) of Electrical and Electronics Engineering Department of BUET. The data of 12 m...Two solar water heaters of 100 liter and 200 liter were installed on the roof-top of electronics laboratory at Old Academic Building (OAB) of Electrical and Electronics Engineering Department of BUET. The data of 12 months have been collected and analyzed in this paper. It is found that the incoming hot tap water is about 30℃ higher than the room temperature during day time during winter months. This is about 25℃ in afternoon hours.展开更多
A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of...A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.展开更多
This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as...This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as supporting material was modified by moderate oxidant of H_(2)O_(2)with different concentrations,and then sta-bilized stearic acid(SA)to prepare composite PCMs through vacuum impregnation.It found that CSC support causes a 15.70%improvement of SA loadage after treated by 15%H_(2)O_(2)due to coefficient enhancement by phys-ical interaction and surface modification.The modified CSC 15 support appears more super macropores which contribute to the impregnation of SA than non-modified CSC 0 support verifying from SEM and BET results.And the content of oxygen functional groups was increased after oxidation modification,also motivating SA stabiliza-tion by hydrogen bond interaction in XPS analysis.FTIR results proved there is no chemical reaction happened between SA and CSC.Moreover,the latent heat and phase transition temperature of the as-prepared SA/CSC 15 composite are 76.69 J g^(−1)and 52.52℃,respectively.All composites exhibit excellent thermal stability under a working temperature of 180℃and form stability during phase change.Thermal energy storage-release test within 70℃presents the composite has fast heat transfer efficiency than pure SA.The composite filled in TSWH system has 0.75 W m^(−1)K^(−1)thermal conductivity which is 2.88 times higher than that of pure SA(0.26 W m^(−1)K−1).Besides,the TSWH system with a flow rate of 0.004 kg s^(−1)could heat water effectively after sunset and the energy obtained from the thermal storage system within 1830 s testing times is about 0.15 kW h.In all,SA/CSC composite with good physical-thermo properties has potential in thermal energy storage application,especially in solar energy storage.展开更多
In this paper,interval number optimization and model predictive control are proposed to handle the uncertain-but-bounded parameters in electric water heater load scheduling.First of all,interval numbers are used to de...In this paper,interval number optimization and model predictive control are proposed to handle the uncertain-but-bounded parameters in electric water heater load scheduling.First of all,interval numbers are used to describe uncertain parameters including hot water demand,ambient temperature,and real-time price of electricity.Moreover,the traditional thermal dynamic model of electric water heater is transformed into an interval number model,based on which,the day-ahead load scheduling problem with uncertain parameters is formulated,and solved by interval number optimization.Different tolerance degrees for constraint violation and temperature preferences are also discussed for giving consumers more choices.Furthermore,the model predictive control which incorporates both forecasts and newly updated information is utilized to make and execute electric water heater load schedules on a rolling basis throughout the day.Simulation results demonstrate that interval number optimization either in day-ahead optimization or model predictive control format is robust to the uncertain hot water demand,ambient temperature,and real-time price of electricity,enabling customers to flexibly adjust electric water heater control strategy.展开更多
Solar water heating systems have been widely used around the world.However,exposure to sunlight can overheat the device,affecting the efficiency and durability of the system.This article proposes an adaptive deck cont...Solar water heating systems have been widely used around the world.However,exposure to sunlight can overheat the device,affecting the efficiency and durability of the system.This article proposes an adaptive deck controller that protects the system from overheating without compromising the availability of domestic hot water.Solar water heaters are considered one of the most effective ways to reduce a home’s carbon footprint.They are a renewable energy source that reduces reliance on fossil fuels and saves money.Thus,this paper aims to develop a dynamic cover for solar water heaters that prevent overheating using an artificial neural network to optimize the design of control systems.Based on a self-organizing map network,the controller automatically adjusts the temperature of the solar collector through a fabric screen covering the main subsystems,depending on many parameters such as weather conditions,collector temperature and domestic hot water depending on demand.A suggested technique of four different shade percentages(0%,20%,25%or 32%)can avoid overheating and maintain the amount of hot water the home needs.Although renewable energy is free,proper controls are required to ensure maximum efficiency or proper use.In addition,the control of renewable energy leads to longer service life.展开更多
A new air-water dual source heat pump water heater with heat recovery is proposed.The heat pump system can heat water by using a single air source,a single water source,or air-water dual sources.The water is first pre...A new air-water dual source heat pump water heater with heat recovery is proposed.The heat pump system can heat water by using a single air source,a single water source,or air-water dual sources.The water is first pre-heated by waste hot water,then heated by the heat pump.Waste heat is recovered by first preheating the cold water and as water source of the heat pump.According to the correlated formulas of the coefficient of performance of air-source heat pump and water-source heat pump,and the gain coefficient of heat recovery-preheater,the formulas for the coefficient of performance of heat pump in six operating modes are obtained by using the dimensionless correspondence analysis method.The system characteristics of heat absorption and release associated with the heat recovery-preheater are analyzed at different working conditions.The developed approaches can provide reference for the optimization of the operating modes and parameters.The results of analysis and experiments show that the coefficient of performance of the device can reach 4-5.5 in winter,twice as much as air source heat pump water heater.The utilization of waste heat in the proposed system is higher than that in the system which only uses waste water to preheating or as heat source.Thus,the effect of energy saving of the new system is obvious.On the other hand,the dimensionless correspondence analysis method is introduced to performance analysis of the heat pump,which also has theoretical significance and practical value.展开更多
Wind power curtailment is of great importance with the increase of large-scale wind power connected to the grid. A new concept of redundant wind power accommodated by dispatching electric water heaters(EWHs) is develo...Wind power curtailment is of great importance with the increase of large-scale wind power connected to the grid. A new concept of redundant wind power accommodated by dispatching electric water heaters(EWHs) is developed in the paper. Precise predictions of wind power and EWHs load power are the basis for this work. A hybrid multi-kernel prediction approach integrating an adaptive fruit fly optimization algorithm(AFOA)and multi-kernel relevance vector machine(MKRVM) is proposed to deal with the sample distribution of multisource heterogeneous features uncovered by an energy entropy method, where AFOA is used to determine the kernel parameters in MKRVM adaptively and avoid the arbitrariness. For the large computation of the prediction approach, parallel computation based on the Hadoop cluster is used to accelerate the calculation. Then, an economic dispatching model for accommodating wind power is built taking into account the penalty of curtailed wind power and the operation cost of EWHs. The proposedscheme is implemented in an intelligent residential district.The results show that the optimization performance of the hybrid prediction approach is superior to those of four usual optimization algorithms in this case. Regular or orderly scheduling of EWHs enables accommodation of superfluous wind power and reduces dispatch cost.展开更多
文摘A thermoeconomic optimization analysis is presented yielding simple algebraic formulae for estimating the optimum number of feed water heater and optimal area distribution among the feed water heaters for thermal power plants. The P1-P2 method is used in the present study, together with the thermoeconomic analyses of feed water heaters.
文摘Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar water heaters as a result of their greater surface area exposed for sunlight absorption. Water-in-glass evacuated tube solar water heaters are widely used as compared to heat-pipe solar water heaters due to their short payback periods. In this study, the performance of water-in-glass evacuated tube solar water heater is investigated through experiments under the climatic conditions in Kenya. The results revealed a daily efficiency range of 0.58 - 0.65 and a daily final outlet temperature greater than 55<span style="white-space:normal;">°</span>C given an initial temperature of 25°C.
基金Supported by Hunan Science and Technology Office(06wk3023)National High Technology Research and Development Program of China(2006AA05Z229)Project-sponsored by SRFfor ROCS,SEM
文摘A new kind of thermoelectric heat pump water heater for kitchens exhaust heat recovery was presented,and its performances were investigated under different operating voltages.The experiment results show that the coefficient of performance decreases and the temperature difference between the hot and cold sides becomes larger with the increase of the operating voltage,but the heating time becomes short.The higher the temperature of water,the greater the temperature difference between the hot and cold sides,leading to a smaller coefficient of performance.Under an exhaust temperature of 36 ℃,the coefficient of performance decreases from 1.66 to 1.22 when the temperature of water increases from 28 ℃ to 46 ℃ with operating voltage 16 V.Performance tests illustrate that,compared with the conventional electrical water heaters,the new kind of thermoelectric heat pump water heater is more coefficient.
文摘In order to meet the demands of service life and the synthetical performance/price ratio of stainless steel in the solar water heater industry,the low molybdenum ultra-pure ferritic stainless steel(FSS) B445J1M was developed at Baosteel.In this study,comparative studies were carried out on the mechanical properties,the formability and the corrosion resistance of B445J1M,304 and 444,and the advantages and application fields of B445J1M were summarized.
文摘China is the largest solar water heater producer and market in the world.Despite the fast growth and an installed capacity that accounts for the majority of the global gross,China's per capita solar hot water capacity is still very low,implying a huge margin of market potential;and the recognition of the industry in the global market is handicapped by the scattered scale of production and inconsistent product quality.To ensure continued growth of China's solar water heating(SWH) industry,Chinese Government has established a series of national SWH standards,three national testing centers,and a certification program to lay the foundation for the development of the Golden Sun product labeling system.China General Certification Center(CGC) developed the Golden Sun product certification and labeling system on a pass/fail basis evaluating with established criteria.The system was designed to help manufacturers acclimate to explicit consistent requirements and to identify and fix the deficiencies in the design and execution of the program itself.Timely revision and integration of the national standards are recommended to accommodate the test procedures and requirements to new technologies and the evolving SWH market.Strict implementation of the Golden Sun certification and labeling system are suggested to avail improving the quality control and forging internationally reputable brands of Chinese solar water heating products.
文摘In this paper we describe an integrated collector storage solar water heater for the North Western region of India for use as domestic water heater during the winter season and present the experimental results of temperature stratification. The system consists of a steel water storage tank with azimuthal orientation such that its walls face south east, south west, north east and North West directions. The sunlit walls (south east and south west) and the top cover surface of the storage tank are covered with transparent insulation material (TIM) and the off-sunlit sides with opaque insulation. Experimental results show that the top layer is at the highest temperature. The top layer is drained using a new design of the outlet. The system can be used in rural areas or as a pre heater in more affluent households. The system can return the cost of conversion of the storage tank into a Solar Water Heater in one winter season by saving the cost of electrical energy required for heating water during winter months.
文摘Two solar water heaters of 100 liter and 200 liter were installed on the roof-top of electronics laboratory at Old Academic Building (OAB) of Electrical and Electronics Engineering Department of BUET. The data of 12 months have been collected and analyzed in this paper. It is found that the incoming hot tap water is about 30℃ higher than the room temperature during day time during winter months. This is about 25℃ in afternoon hours.
基金the National Natural Science Foundation of China(No.51776117)。
文摘A new type of microchannel condenser applied in the air source heat pump water heater(ASHPWH)with cyclic heating was proposed in this study.The operating performance of the ASHPWH was frst tested.Then,the structure of the microchannel condenser was optimized with the implement of vortex generators.Finally,a numerical model of the ASHPWH was established and the optimized microchannel condenser was studied.The experimental results showed that the average coefficient of performance(COP)of the 1HP(735 W)ASHPWH reached 3.48.In addition,the optimized microchannel condenser could be matched with a 3 HP(2430W)ASHPWH with an average heating capacity of 10.30 kW,and achieving an average COP of 4.24,14.6%higher than the limit value in the national standard.
基金This work was supported by the National Natural Science Founda-tion of China(51874047,51504041)the Training Program for Excel-lent Young Innovators of Changsha(kq1802007)+2 种基金the Fund for Univer-sity Young Core Instructors of Hunan Provincethe Outstanding Youth Project of Hunan Provincial Department of Education(18B148)and the Hunan Province 2011 Collaborative Innovation Center of Clean Energy and Smart Grid.
文摘This work presents a cost-effective and environment-friendly form-stabilized phase change material(PCM)and corresponding solar thermal application in the tankless solar water heater(TSWH).Coconut shell charcoal(CSC)as supporting material was modified by moderate oxidant of H_(2)O_(2)with different concentrations,and then sta-bilized stearic acid(SA)to prepare composite PCMs through vacuum impregnation.It found that CSC support causes a 15.70%improvement of SA loadage after treated by 15%H_(2)O_(2)due to coefficient enhancement by phys-ical interaction and surface modification.The modified CSC 15 support appears more super macropores which contribute to the impregnation of SA than non-modified CSC 0 support verifying from SEM and BET results.And the content of oxygen functional groups was increased after oxidation modification,also motivating SA stabiliza-tion by hydrogen bond interaction in XPS analysis.FTIR results proved there is no chemical reaction happened between SA and CSC.Moreover,the latent heat and phase transition temperature of the as-prepared SA/CSC 15 composite are 76.69 J g^(−1)and 52.52℃,respectively.All composites exhibit excellent thermal stability under a working temperature of 180℃and form stability during phase change.Thermal energy storage-release test within 70℃presents the composite has fast heat transfer efficiency than pure SA.The composite filled in TSWH system has 0.75 W m^(−1)K^(−1)thermal conductivity which is 2.88 times higher than that of pure SA(0.26 W m^(−1)K−1).Besides,the TSWH system with a flow rate of 0.004 kg s^(−1)could heat water effectively after sunset and the energy obtained from the thermal storage system within 1830 s testing times is about 0.15 kW h.In all,SA/CSC composite with good physical-thermo properties has potential in thermal energy storage application,especially in solar energy storage.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51477111)the National Key Research and Development Program of China(Grant No.2016 YFB-0901102).
文摘In this paper,interval number optimization and model predictive control are proposed to handle the uncertain-but-bounded parameters in electric water heater load scheduling.First of all,interval numbers are used to describe uncertain parameters including hot water demand,ambient temperature,and real-time price of electricity.Moreover,the traditional thermal dynamic model of electric water heater is transformed into an interval number model,based on which,the day-ahead load scheduling problem with uncertain parameters is formulated,and solved by interval number optimization.Different tolerance degrees for constraint violation and temperature preferences are also discussed for giving consumers more choices.Furthermore,the model predictive control which incorporates both forecasts and newly updated information is utilized to make and execute electric water heater load schedules on a rolling basis throughout the day.Simulation results demonstrate that interval number optimization either in day-ahead optimization or model predictive control format is robust to the uncertain hot water demand,ambient temperature,and real-time price of electricity,enabling customers to flexibly adjust electric water heater control strategy.
基金The authors would like to thank the Higher Center for Research(HCR)of the Holy Spirit University of Kaslik(USEK)the National Council for Scientific Research in Lebanon(CNRS-L)for funding this project。
文摘Solar water heating systems have been widely used around the world.However,exposure to sunlight can overheat the device,affecting the efficiency and durability of the system.This article proposes an adaptive deck controller that protects the system from overheating without compromising the availability of domestic hot water.Solar water heaters are considered one of the most effective ways to reduce a home’s carbon footprint.They are a renewable energy source that reduces reliance on fossil fuels and saves money.Thus,this paper aims to develop a dynamic cover for solar water heaters that prevent overheating using an artificial neural network to optimize the design of control systems.Based on a self-organizing map network,the controller automatically adjusts the temperature of the solar collector through a fabric screen covering the main subsystems,depending on many parameters such as weather conditions,collector temperature and domestic hot water depending on demand.A suggested technique of four different shade percentages(0%,20%,25%or 32%)can avoid overheating and maintain the amount of hot water the home needs.Although renewable energy is free,proper controls are required to ensure maximum efficiency or proper use.In addition,the control of renewable energy leads to longer service life.
基金supported by the National Natural Science Foundation of China (Grant No. 51076147)
文摘A new air-water dual source heat pump water heater with heat recovery is proposed.The heat pump system can heat water by using a single air source,a single water source,or air-water dual sources.The water is first pre-heated by waste hot water,then heated by the heat pump.Waste heat is recovered by first preheating the cold water and as water source of the heat pump.According to the correlated formulas of the coefficient of performance of air-source heat pump and water-source heat pump,and the gain coefficient of heat recovery-preheater,the formulas for the coefficient of performance of heat pump in six operating modes are obtained by using the dimensionless correspondence analysis method.The system characteristics of heat absorption and release associated with the heat recovery-preheater are analyzed at different working conditions.The developed approaches can provide reference for the optimization of the operating modes and parameters.The results of analysis and experiments show that the coefficient of performance of the device can reach 4-5.5 in winter,twice as much as air source heat pump water heater.The utilization of waste heat in the proposed system is higher than that in the system which only uses waste water to preheating or as heat source.Thus,the effect of energy saving of the new system is obvious.On the other hand,the dimensionless correspondence analysis method is introduced to performance analysis of the heat pump,which also has theoretical significance and practical value.
基金supported by National Natural Science Foundation of China (No. 51407077)Fundamental Research Funds for the Central Universities of China (No. 2017MS095)Technology Project of State Grid Corporation of China Headquarter (No. 5204BB16000F)
文摘Wind power curtailment is of great importance with the increase of large-scale wind power connected to the grid. A new concept of redundant wind power accommodated by dispatching electric water heaters(EWHs) is developed in the paper. Precise predictions of wind power and EWHs load power are the basis for this work. A hybrid multi-kernel prediction approach integrating an adaptive fruit fly optimization algorithm(AFOA)and multi-kernel relevance vector machine(MKRVM) is proposed to deal with the sample distribution of multisource heterogeneous features uncovered by an energy entropy method, where AFOA is used to determine the kernel parameters in MKRVM adaptively and avoid the arbitrariness. For the large computation of the prediction approach, parallel computation based on the Hadoop cluster is used to accelerate the calculation. Then, an economic dispatching model for accommodating wind power is built taking into account the penalty of curtailed wind power and the operation cost of EWHs. The proposedscheme is implemented in an intelligent residential district.The results show that the optimization performance of the hybrid prediction approach is superior to those of four usual optimization algorithms in this case. Regular or orderly scheduling of EWHs enables accommodation of superfluous wind power and reduces dispatch cost.
